Glass fibers are useful in a variety of technologies. For example, glass fibers are commonly used as reinforcements in polymer matrices to form glass fiber rein forced plastics or composites because they provide dimensional stability as they do not shrink or stretch in response to changing atmospheric conditions. In addition, glass fibers have high tensile strength, heat resistance, moisture resistance, and high thermal conductivity.
Typically, glass fibers are formed by attenuating streams of a molten glass material from a bushing or orifice. The molten glass may be attenuated by a winder which collects gathered filaments into a package or by rollers which pull the fibers before they are collected and chopped. An aqueous sizing composition is typically applied to the fibers after they are drawn from the bushing. Once the fibers are treated with the sizing composition, they may be cried in a package or chopped strand form. Drying the fibers evaporates the liquid medium and deposits the size as a residue lightly coating the surface of the glass fiber.
Conventional sizing compositions typically contain one or one film forming polymeric or resinous components, glass-resin coupling agents, and one or more lubricants dissolved or dispersed in a liquid medium. The film forming component of the size composition is desirably selected to be compatible with the matrix resin or resins in which the glass fibers are to be embedded. Epoxy resins and polyurethanes have been used as film forming components in size compositions. Epoxy resins are typically utilized where the fibers are to be used for reinforcing articles made from epoxy resins or vinyl esters of epoxy resins, such as by impregnating continuous multifilament glass fiber strands with a curable resin composition, winding the glass fiber strands about a suitable form, and then curing the matrix resin to produce a glass fiber rein forced article Such as a pipe or tank.
U.S. Pat. No. 4,104,434 to Johnson describes a sizing composition that contains a water emulsifiable resin system such as an epoxy resin, an aliphatic monocarboxylic acid, and an aliphatic polycarboxylic acid.
U.S. Pat. No. 4,107,118 to McCoy describes a glass sizing composition that contains an epoxy resin emulsion, a polyvinylpyrrolidone, and a polyethylene glycol ester monooleate. The patentee asserts that the sizing composition is particularly suitable for use in epoxy filament winding.
U.S. Pat. No. 4,140,833 to McCoy discloses a glass sizing composition that includes an epoxy resin emulsion, a polyvinylpyrrolidone, α-metthacryloxypropyltriethoxysilane, and a polyethylene glycol ester monostearate. The patentee asserts that the sizing composition is particularly suitable for continuous pultrusion.
U.S. Pat. No. 4,305,742 to Barch et al. discloses a sizing composition for treating glass fibers that includes a phenolic epoxy resin, the reaction product of a partial ester of polycarboxylic acid that contains one or more unesterified carboxyl groups with a compound containing more than one epoxy group, a lubricant, emulsifiers or wetting agents, one or more silane coupling agents, and water.
U.S. Pat. No. 4,394,418 to Temple describes an aqueous sizing composition that includes a polyvinyl acetate silane copolymer, an epoxy polymer, one or more lubricants, an organosilane coupling agent, one or more non-ionic surfactants, a hydrocarbon acid, and water. The organosilane coupling agent may be an amino-organosilane coupling agent, a lubricant modified aminosilane coupling agent, an epoxy containing silane coupling agent, or a mixture of two or more of these coupling, agents. Optionally, the sizing composition may also include a polyethylene-containing polymer, and/or a wax.
U.S. Pat. No. 4,448,910 to Haines et al. discloses an aqueous sizing composition for glass fibers that contains an emulsified epoxy resin, a lubricant, and 3-chloropropyltrimethoxysilane.
U.S. Pat. No. 4,448,911 to Haines et al. describes an aqueous sizing composition for glass fibers that has an emulsified epoxy resin as the film former, an emulsified mineral oil as the lubricant, glycidoxyalkyl and/or haloalkylsilanes as coupling agents, an amide antistatic agent, and polyvinlylpyrrolidone.
U.S. Pat. No. 4,656,084 to McCoy el al. discloses all aqueous sizing composition for glass fibers that contains epoxy- and methacrylyl-functional organosilanes, a fiber forming polymer such as an epoxy resin, a lubricant, and a pH regulator. McCoy el al. teach that the sizing composition is particularly suitable for glass fiber reinforcements for filament winding and pultrusion applications.
U.S. Pat. No. 4,933,381 to Hager discloses a size composition for sizing small diameter glass fibers. The sizing composition includes an epoxy film former resin, a non-ionic lubricant, a cationic lubricant, at least one organosilane coupling agent, at least one volatile or nonvolatile acid, and water.
U.S. Pat. No. 5,038,555 to Wu et al. discloses a size composition that includes an epoxy as the film former, at least one emulsifying agent, at least one fiber lubricant, at least one organofunctional metallic coupling agent, polyvinylpyrrolidone, a water dispersible or emulsifiable polyethylene, and water.
U.S. Pat. No. 5,262,236 to Brach et al. describes an aqueous size composition for glass fibers that includes an epoxy resin, a coupling agent, and crystalline pentaerythritol. Brannon asserts that the sizing composition is particularly suitable for glass fiber reinforcements for filament winding and pultrusion applications.
U.S. Pat. No. 6,270,897 to Flautt et al. discloses a Sizing composition that contains a combination of at least one diol organosilane and at least one triol organosilane. The sizing composition may also contain film-forming polymeric materials such as epoxy resins and lubricants.
The sizing composition is applied to the fibers to reduce interfilament abrasion and breakage during subsequent processing and to improve the compatibility of the fibers with the matrix resin that is to be reinforced. In addition to improving the processability of the fiber and the fiber-polymer coupling, the sizing composition should also enhance the physical properties of the composite article formed from the reinforced fiber. Accordingly, in view of the dual role of the sizing compositions in improving the processability of the fibers while improving the physical properties of the resulting composite and the wide variety of polymeric materials that can be reinforced with glass fibers, a continuing need exists in the art for specifically tailored sizing corn positions that provide enhanced physical properties and processing characteristics to reinforced composite articles.